Abrasive wheel



Jan. 28, 1947. R. B. SCRIMGEOUR 2'41498l ABRASIVE WHEEL Filed June 18. 1944 INVENTOR.

ROBERT Bficnmecoull BY ATTORNEY.

Patented Jan. 28, 1947 YUNITED STATES PATENT OFFICE AnnAsIvE WHEEL Robert B. Scrimgeour, Trenton, N. J. Application June 13, 1944, Serial No. 540,086

1 Claim. 1

My invention is an improved flexible abrasive Wheel designed for polishing, buffing or grinding, and particularly for polishing, bufiing or grinding irregular surfaces. My invention also includes a method of making abrasive wheels with desired degrees of flexibility and abrasive capacity.

In accordance with my invention an abrasive fabric is rumpled to form a cellular body or mass containing air cells formed by wall sections of irregular size, shape and angularity, and portions of which are bonded together to maintain the structural integrity of the mass without im pairing the abrasive capacity of the bulk of the surface of the fabric.

The fabric may be any suitable sheet material,

such as a textile, paper, felt, or leather coated or impregnated on one or both sides with abrasive particles or with abrasive particles incorporated therein during manufacture. The abrasive particles may be of any desired size and quality, as,-

for instance, diamond dust, emery powder, sand, grains of silicon carbide, etc.

The abrasive sheet material may be rumpled by bending, twisting, crumpling or otherwise distorting the sheet material so as .to form a cellular mass of random porous texture, and an abrasive wheel embodying my invention may comprise a single mass or numerous masses compacted together and connected by random bonds.

The bonds are preferably provided by adhesive material spotted at random on the abrasive fabric, preferably after the rumpling thereof, and preferably by tumbling the rumpled masses in contact with a suitable adhesive, such as animal or vegetable glue, shellac, resinous condensation products, silicate of soda, or the like. The bonding material may, however, be applied by spraying, dipping or brushing so as not to completely neutralize the abrasive action of the fabric surfaces.

The rumpled and adhesive treated material is compacted by pressure to provide a porous, spongy mass retaining sufficient flexibility for the particular use for which the particular wheel is designed.

In the preferred practice of my invention, the flexible abrasive fabric is haphazardly rumpled into irregularly shaped porous lumps containing numerous air spaces enclosed by flexible walls of varied and irregular size, shape and relative angularity. The fabric is preferably divided into relatively small parts before rumpling so that the lumps are relatively small, and, preferably, of approximately similar size.

The lumps of rumpled material have applied thereto random spots of adhesive so that the lumps of rumpled material are coated with irregular spots of adhesive primarily on the outer surfaces of the lumps, and with little penetration of the adhesive to the inner walls of the air spaces.

The adhesive coated lumps are then compacted into a wheel of desired shape under suflicient pressure to impart bodily cohesion between the lumps and the walls thereof but insufficient to eliminate the air spaces in and among the lumps from which the wheel is formed. The wheels are held compacted until the adhesive has sufficiently solidified to maintain the structural cohesion of the wheel. The wheels are preferably formed as annular rims containing an axial aperture for the reception of a hub. The flexibility or rigidity of the wheel will be dependent primarily upon the type of fabric, the type of adhesive, and the degree of compaction used in the preparation of the Wheel and the radial width of the rim surrounding the hub.

The Wheels may be made of suflicient flexibility as to conform with the irregularities of irregular surfaces polished or buffed thereby, or made of suflicient rigidity to act as a flexible grinding wheel.

The characteristic features and advantages of my invention will further appear from the following description and the accompanying drawing in illustration thereof.

In the drawing, Fig. 1 is a fragmentary view of a strip of abrasive sheet material from which a flexible abrasive wheel may be made in accordance with my invention; Fig. 2 shows fragmentary sections of the sheet shown in Fig. l rumpled into lumps or small masses; Fig. 3 is a diagrammatic transverse sectional view of a tumbler containing an adhesive film against which rumpled lumps of abrasive sheet material are rolled for spot-coating with adhesive; Fig. 4 is a diagrammatic transverse sectional view of a mold containing spot-coated rumpled lumps of sheet material compressed by a follower; Fig. 5 is an edge view of a flexible abrasive wheel embodying my invention; Fig. 6 is a diametral, sectional view of the flexible abrasive wheel shown in Fig. 5, and

Fig. I is a sectional view of half a wheel taken on the line 'l-'| of Fig. 1.

In the embodiment of my invention illustrated in the drawing, sheets of abrasive cloth I, having abrasive particles on both surfaces, as shown in Fig. 1, are rumpled or crumpled into approximately similar sized masses of cellular lumps 2 of irregular contour and containing air spaces or pockets surrounded by walls of irregular size,

shape, and relative angularity formed by the crumpling of the abrasive cloth.

The cellular lumps are random spot-coated with an adhesive which is preferably applied by spraying the liquid adhesive from an axially extending pipe 3 against the inner wall of a rotating drum or tumbler 4 so as to form a thin film of adhesive thereon, which is transferred to the outer surfaces of lumps 2 when the latter are tumbled in the bottom of the rotating drum. The adhesive adheres at random on the surfaces of the lumps, with but slight penetration of the adhesive into the lumps and with but relatively little impairment of the abrasive character of the bulk of the area of the abrasive cloth embodied in the respective lumps.

A suitable number of the adhesive spotted lumps are then deposited in a wheel mold having an annular wall 5 and a bottom 6 provided with a centering pin 1 on which an axial former 8 may be centered before the deposition of the adhesive lumps 2 so as to leave a hub hole in the wheel or rim. Preferably a liner 9 is also placed in the bottom of the mold around the former 8 before the deposition of the adhesive-spotted lumps so as to prevent the adhesion of the lumps to the bottom of the mold.

After adhesive lumps to form a wheel or rim of desired compaction and thickness had been deposited in the mold, a former i0, having on its under surface a temporary liner ii, is pressed against the top of the rumpled material with sufiicient force to provide a desired degree of compaction but insufficient to eliminate all of the air pockets formed by the rumpling oi the and a hub l2 inserted in the axial aperture formed in the wheel by the former 8. Cheeks l3 and I4 may be attached to the hub in any suitable manner, as for instance by screws [5, or one of the cheeks may be formed integrally with the hub.

The liners 9 and II may be formed of sheet material, such as paper, which will not interfere with the utilization of the wheel for its intended purpose of polishing, buffing or grinding, or the liners may be stripped from the wheel before the utilization thereof.

A wheel embodying my invention has a cellular or honeycombed interior with walls of irregular size, shape and inclination extending haphazardly in all directions, as indicated somewhat diagrammatically in Figs. 6 and 7, and the periphery and sides of the wheel are likewise composed of wall sections of irregular size, shape and inclination haphazardly arranged both initially and as the wheel is worn down. The flexibility of the sheet material and the cellularity of the walls provide a limber and pliant wheel which may be used until substantially all of the impregnated fabric has been worn out.

Having described my invention, I claim:

A flexible abrasive wheel comprising a hub and a plurality of separate bodies each formed by a haphazardly rumpled piece of abrasivecoated fabric, each of said rumpled pieces of abrasive-coated fabric having numerous portions folded upon themselves to provide in the body numerous cavities of irregular shapes distributed throughout the body, said bodies being substantially uniformly distributed around the hub of the wheel and the bodies and hub being secured together by an adhesive at the spaced small areas where the bodies make contact with one another and with the hub.

ROBERT B. SCRIMGEOUR. 

